1. Field of the Invention
The present invention relates generally to portable time conversion devices and more particularly to devices that provide the capability of calculating local time, both standard and adjusted, at various places in the world.
2. Description of the Related Art
Although many time calculating or displaying inventions have been introduced over the years, there are still some problems that need to be solved in order to satisfy the needs of users such as frequent travelers, businessmen, international disaster relief workers, and many others. Various inventions have their own strengths, yet it seems that some important problems have not been satisfactorily dealt with.
The following problems have been considered, as the present invention has been developed.
1. Some inventions do not have much space for a list of geographical locations.
2. There are countries such as the U.S.A. that use adjusted (daylight saving) time during part of a year. Unless this problem is properly dealt with, time calculation between these places and other countries that do not change time would be inaccurate or difficult, if not impossible. Moreover, some states or cities within these countries such as Arizona do not adjust time at all while other states adjust time. This can be confusing or may cause serious problems.
3. For places that are not mentioned or addressed on a time calculating device, one has to rely on other methods. Otherwise, one simply cannot calculate the time.
4. When there is ambiguity, how does a user make decisions? For example, when a location is situated between two different 15 degree longitudes, how does the user know the correct choice? When a big country such as the People's Republic of China stretches East to West covering many “time zones” or multiples of 15 degree longitude, how does the user know which time they use or how many time zones they have in the country? Interestingly, China, as large as the contiguous 48 states of the United States, has only one time, which is centered on the capital city, Beijing.
5. For many people living in a country where they have only one time zone or use only one time, it is mind boggling that a country has more than one time. Many Asians seem to be puzzled when they hear that the U.S. has multiple time zones, while many Americans seem to be surprised when they hear that China, a big country as large as the U.S. is using only one time and that they do not have daylight saving time, that is, they use only one time throughout a year.
6. Use of a one half (½) hour time zone also can cause confusion. Not many people living outside of India may know that this country with more than one billion population is five and half (5½) hours ahead of the Greenwich Mean Time (GMT). This one half (½) hour time may limit the use of many time calculating devices. It is noted that Greenwich Mean Time (GMT) is the same as UTC (Coordinated Universal Time) or UT (Universal Time).
7. What about a general question such as “What time is it now in Australia?” Not many people in Asia or the U.S. may know that Australia has three time zones, not to mention that one of these three time zones uses one half hour time. Interestingly, they have three time zones, GMT+8, +9.5, and +10.
8. The use of 15 degree longitude for one hour time zone does not necessarily match with each time zone. For example, in South America, some parts of western Brazil are further East than most of Argentina but Argentina time is one hour ahead of these parts in Brazil.
9. It is necessary to show the bird's eye view of time zones of the world. For example, if one wants to see how many time zones are in the U.S., Australia, India, or China, it is not easy to learn quickly from an ordinary dial type or other slide rule type world time calculators. Also, determining time difference between a particular location and the Greenwich Mean Time should not be too difficult or cumbersome.
10. In order to deal with detailed information, it is necessary to have sufficient space. However, if it takes too much space, it is not easy to carry this calculator or displayer. One needs a system that can be effective and informative, yet, it has to be small enough to be carried around relatively easily.
11. In order to deal with people living in various countries and cultures, more than one language or script should be considered.
Thus, in order to deal with all the aforementioned issues, it is necessary to show the bird's eye view of the world as well as the detail list of locations using a particular time. Furthermore, for those who are not familiar with world time, it would be good to provide some types of explanation of important concepts or background information (such as the definition and history of daylight saving time). Index of many countries and cities of the world is also needed for quick references.
U.S. Pat. No. 7,050,357, issued to Garcia, entitled “Global Time Indicator” discloses a global time indicating calculator that has a clock member with a rotating dial for calculating global standard time and advanced time in various international time zones. Indicia printed on the face of the dial and corresponding boxes on oppositely opposed faces of the calculator can be easily referenced to determine time of day at selected locations throughout the world. The faces have recesses therein to interchangeably accommodate the clock member whereby the calculator can be modified to calculate the time of day during either standard time or advanced time periods. But it may be difficult for non-Americans who do not know the definition of some concepts and abbreviations used on the device. For example, someone in Asia who is not familiar with American time system may wonder “What are the PT, MT, CT, ET?” or “When do they use the advanced time?” This invention also seems to have problem with space. If a location is not listed on the device, how can a user find the correct time? Since names are not arranged alphabetically and no index seems to be provided, one has to struggle to find the desired location. If one wants to know the time of a country instead of a city, it is not easy unless he or she is quite familiar with world geography.
U.S. Pat. No. 6,330,970, issued to Whalen, entitled, “Global Time Calculator” discloses a global time calculator that includes an insert and a sleeve. The insert is marked on both its sides (or on a single page slide insert on one side) with vertical columns of incremental time designations, and may or may not contain a stop mechanism. The insert is slidable and connected with the sleeve so as to be shiftable in a vertical direction. Both sides of the sleeve (or in some embodiments a single side of the sleeve) have areas for obscuring vertically aligned time designations that are in excess of unobscured time designations. But this device does not handle daylight saving time and time zones that use one half hour time.
U.S. Pat. No. 5,303,956, issued to Zoland, entitled, “Time Zone Conversion Chart for Card, Luggage Tag or Key Chain” discloses a travel document folder, card case or luggage tag that features a time zone conversion chart. But this device does not provide many locations due to limited space and size of the dial.
U.S. Pat. No. 5,007,033, issued to Kubota et al., entitled, “World Timepiece” discloses a world timepiece for normally displaying the time of a home city and for selectively displaying the time of another city situated in another time zone. The world timepiece includes a plurality of selector switches corresponding to main cities located in different time-lag zones into which the world is divided. A display unit normally displays the time of the user's home city and, upon actuation of one of the selector switches, the display unit displays the time of the selected city designated by the actuated selector switch. A city of an arbitrary time-lag zone can be stored in an assigned city storage circuit, and the time of the assigned city can be displayed by the display unit by actuating an optional switch. This invention does not list many cities that belong to the same time zone. A foreigner who does not have extensive knowledge of the regional geography such as various time zones of the U.S. may have difficulty using it. Another problem is that use of daylight saving time is not clearly addressed. For example, most of the U.S. uses daylight saving time part of a year, but there are exceptions for some areas and cities.
U.S. Pat. No. 4,681,460, issued to Nishimura, entitled, “World Time Watch” discloses a world time watch that has a liquid crystal display device including a time zone display and a time display. The time zone display is provided to display the time difference between a selected place and the Greenwich Mean Time, and the time display is provided to display the time of the place corresponding to the time difference displayed in the time zone display. A printed place name list is provided around the liquid crystal display device. The place name list includes a plurality of numbers each of which represents the corresponding time difference of a particular place. The Nishimura device does not deal with half hour time zone and adjusted time (daylight saving time). Also, space allocated for each time zone is not enough.
U.S. Pat. No. 4,032,754, issued to Ageton, entitled, “Global Time System” discloses a global time system having a first disc divided into twenty-four equal sections, each section being formed by lines extending radially from the center of the first disc. Each line forming the sections represents a line of longitude. Circles are concentrically disposed about the center of the disc and extend outward to the edge of the disc. The circles, representing lines of latitude, cross over each of the twenty-four lines of longitude to form geographic spaces between the lines of longitude and latitude. A time disc is rotatably mounted to the center of the first disc and has twenty-four lines equally spaced from each other on the outside edge. Reference symbols are positioned on the first disc and adjacent to the outside edge of the time disc, with the reference symbol in each of the twenty-four sections. Identification symbols representing a specific geographic location are disposed within the respective geographic space having the proper longitude and latitude of the location. However, just knowing reference point, longitude and latitude, cannot provide local time accurately. For example, China stretches out multiple time zones but it uses only one time.